EDITOR ’ S CHOICE PROCESS IMPROVEMENTS
NORTHRIDGE PUMPS
Improving Marine Fuel Pump Unloading Performance
Unloading pumps are designed to unload a vessels or oil tankers liquid cargo in the shortest possible amount of time when receiving bulk deliveries of fuel . Oil cargos are typically transported via vessel as it is the most economical form of transportation for bulk cargo transfer and is only surpassed if fuel oils can be transferred via a pipeline eliminating double handling .
An overseas electricity provider contacted us who were having issues unloading light fuel oil ( LFO ) from their barge . The port would regularly receive shipments of oil cargo by vessel which docked over 50M away from the pump . The unit would operate for approximately 16 hours a day , unloading marine fuel for transfer to an oil storage tank located nearly 300M away , which was 10M high .
The customer was experiencing issues with their existing pump which was undersized , noisy and they wanted explore whether a better solution was available to improve marine fuel pump performance and reduce the amount of time vessels were kept moored at port and underutilised whilst discharging cargo .
UNDERSIZED FUEL TRANSFER PUMP
The customer was experiencing several tell tale signs that their pump was undersized . Their screw pump which technology is normally very quiet was producing high levels of noise , there seemed to aeration of the pumped fluid which was detected by their Coriolis Flow Meter , flow rate was less than what the unit was designed for and flow was turbulent meaning there was the potential for inconsistent metering of unloaded fuel as some designs of flowmeters rely on a steady flow of fluid- all symptoms of what happens when a pump is undersized . Furthermore , when the vessel used a pump located on the vessel to boost flow , the aforementioned issues disappeared .
UNLOADING PUMP DESIGN
Unloading pumps are usually designed to produce high flows at low to medium pressures , are self-priming to ensure they
The new unit will speed up tanker offloading and will enable users to have increased control of tanker unloading .
can completely empty a vessels cargo , have a wide viscosity handling to ensure they handle a variety of marine fuel oil derivatives from light distillate , to medium , and heavy fuel oils . Also known as stripping pumps , they enable the complete discharging of fluid from tanks without manual intervention or residue remaining in holds .
They are usually ATEX rated to remove any source of ignition and may have a motor suitable for inverter operation to enable operators to control oil transfer rates in particular when oil viscosity changes . Units can be heat traced as a way of maintaining a fluids viscosity and flow rate or to prevent solidification within the pump head . Similar pumps are also used in fuel bunkering and debunkering operations .
OUR SOLUTION
The client wanted a flow rate of 100M ³ H to 150M ³ H when pumping oil derivatives , be able to draw fluid from the barge and completely strip without manual intervention , whilst varying flow as required
North Ridge specified and selected our NRPZ Self Priming Horizontal Triple Screw Pump complete with ATEX rated Motor suitable for operation via Variable Frequency Drive ( VFD ).
Although pumps can typically only prime a maximum of 9.8M ( based on water ), and even though the suction pipework extended to over 50M away , in this particular application it was well within the capability of the design .
That is because most of the pipework runs horizontally , rather than vertically but care still needs to be taken to ensure that with the fluids viscosity , pipework diameter , and any vertical pipework sections do not amount to a pressure loss high enough to stop the unit functioning as it should .
The marine fuel transfer pump will produce varying flow up to 116M ³ H , be controlled via a Variable Frequency Drive and deliver pressures up to 8 Bar . Coupled to a 45KW ATEX WEG Motor suitable for operation via VFD the unit was assembled with 6 ” inlet and Outlet matching the clients existing pipework .
The new unit will speed up tanker offloading , will enable users to have increased control of tanker unloading and enable the unit to function without any of the issues experienced by the current installation .
If you are experiencing low flows , slow tanker offloading / loading or simply have a unit approaching the end of its useful life and want to see if process improvements can be made - speak to us to see how we can help .
Visit www . northridgepumps . com to see how we can help .
26 PECM Issue 60